One common method for printing images on a receiver member is referred to as electrography. In this method, an electrostatic image is formed on a dielectric member by uniformly charging the dielectric member and then discharging selected areas of the uniform charge to yield an image-wise electrostatic charge pattern. Such discharge is typically accomplished by exposing the uniformly charged dielectric member to actinic radiation provided by selectively activating particular light sources in an LED array or a laser device directed at the dielectric member. After the image-wise charge pattern is formed, resin particles are given a charge, substantially opposite the charge pattern on the dielectric member and brought into the vicinity of the dielectric member so as to be attracted to the image-wise charge pattern to develop such pattern into a patterned image.
Thereafter, a suitable receiver member (e.g., a cut sheet of plain bond paper) is brought into juxtaposition with the marking particle developed image-wise charge pattern on the dielectric member. A suitable electric field is applied to transfer the marking particles to the receiver member in the image-wise pattern to form the desired print image on the receiver member. The receiver member is then removed from its operative association with the dielectric member and the marking particle print image is permanently fixed to the receiver member typically using heat, and/or pressure and heat. Multiple layers or marking materials can be overlaid on one receiver, for example, layers of different color particles can be overlaid on one receiver member to form a layer print image on the receiver member after fixing.
In the earlier days of electrographic printing it was desirable to minimize channel formation during fusing. Under most circumstances, channels are considered an objectionable artifact in the print image. In order to improve image quality, and still produce channels a new method of printing has been formulated in U.S. Publication 2009/0142100. In that invention one or more multi-channeled layers are formed using electrographic techniques. There, use of layered printing, includes possible raised images to create channels capable of allowing movement of a fluid, such as an ink or dielectric, to provide a printed article with, among other advantages, a variety of security features on a digitally printed document.
Microfluidic structures are used for transporting fluid materials around in micro devices. As such there is a need to make routing structure for the fluids. In U.S. Pat. No. 7,216,671 elastomeric layers are made from mold and then stacked. The recesses of the stack allow channels be formed and allow movement of fluids between layers as interconnections. In this invention separate molds are necessary for every layer and a change necessitates new molds be created.
For microfluidic devices to be useful as more than simply as a transport mechanism, it must include other devices. Some of the devices which are commonly incorporated are pumps, valves and mixing regions. In U.S. Pat. Nos. 7,040,338, and 7,169,314 pumps and valves are incorporated. In these patents the separate molds form thin barrier regions in some channels which can be deformed. These barriers can be deformed by the use of pressure. When appropriately shaped, this deformation can act as a valve, preventing the flow of liquid when the barrier is pushed into another channel. If there is an asymmetry in the channel the deformed barrier moves into, then the action can move fluid around. In this case through the use of a periodic deformation, a fluid pump is formed.
Another method of forming a pump in a microfluidic device is illustrated in U.S. Pat. No. 7,540,469. In this method two electrodes are outside the channel. When a voltage is applied between the electrodes the channel is deformed and the pump action occurs. If the voltage is sufficiently high and the channel sufficiently narrow, the deformation can close off the channel. In this case the device is operating as a valve. This microelectromechanical device (MEM) device is integrated into a microfluidic channeled device pre or post-patterned.
Many other devices such as column chromatography column see copending application U.S. application Ser. No. 12/608,047, sensors for detecting fluids or analytes, as well as actuators may be desired. The portions that are in common are the channels which can consist of normal channels as well associated topologic shapes such as splitters, combiners, and mixers. They may even include reservoirs for hold small quantities of fluids until desired.
It is therefore needed a process for making these channels and their associated topologic shapes in a cost efficient and digitally modifiable manner. Some processes have been disclosed such as U.S. Pat. No. 7,095,484 which address this issue. In this patent a micro-mirror device exposes photoresist in a 3 dimensional manner. Subsequent development to generate with an appropriate developer generates the required topologies. It is desired to not need to use wet developers with their associated waste.
It is also necessary to cover layers with a transparent barrier to encapsulate channels as they are built or as a final layer. One way which these barriers can be applied is through lamination of a cover sheet. Microfluidics with laminates is known, as discussed in U.S. Pat. No. 7,553,393. In that patent there is no discussion of the method of manufacture of the channels. The inventors assume one has already generated it and present a lamination method.
There is therefore a need for a process which can generate channels and openings which can be subsequently be encapsulated or top sealed to for fluid paths. The method needs to be both cheap and alignable between layers and most importantly easily reconfigurable to new design. This invention solves these problems.